The hypothesis for this proposal is as follows: a pH responsive novel nano-lipid complex delivery system targeted to lymphoid tissues and HIV host cells will greatly improve cell and tissue selectivity, and thus overcome drug insufficiency of anti-HIV drugs in lymphoid tissues, leading to maximum viral suppression. We will test this hypothesis with a well-established HIV-infected primate model to determine the effects of this novel drug delivery strategy targeted to lymphoid tissue and cells on disease progression. To do so, we will (in aim 1) design pH-responsive lipid-nanoparticles composed of anti-HIV drug combination for enhanced activity in virus host cells. The second aim is designed to compare the most potent anti-HIV nanoparticles containing inhibitors of HIV protease and reverse transcriptase with respect to target tissue and cell selectivity and resident time. The data collected from time-course and dose-dependent pharmacokinetic and tissue localization studies will be used to define a safe and effective dosing schedule for the proof-of-principle study in HIV-infected primates. Finally, we will evaluate the impact of the optimized, pH-responsive anti-HIV nanoparticles on HIV infection and disease progression. The proposed targeted novel drug delivery strategy will accelerate clearance of residual virus in lymphoid tissues and cells, which received limited exposure to orally administered drugs. A primate model is used to probe questions that could not be addressed in humans. The results obtained from these studies hold promise for making a profound advance in anti-HIV drug therapy and providing a proof-of-principle for first-in-human clinical testing. Successful completion of this study will have significant impact on treatment paradigms and outcome of HIV infections. With an established investigative team, we could proceed with first-in-human studies when a positive outcome is achieved.